1. Field of the Invention
Embodiments of the present invention may relate to a dual mode terminal that supports one or more radio systems. More particularly, embodiments of the present invention may relate to a method of providing a simultaneous call service of a dual mode terminal.
2. Background of Related Art
A mobile communication system may be divided into a synchronous system and an asynchronous system. A CDMA 2000 1x Release A system and a 1x EV-DO system are examples of synchronous systems.
The CDMA 2000 1x Release A (hereinafter also the ‘1x Release A’) system was developed for a voice communication service at an early stage of CDMA 2000 development. However, versions of the CDMA 2000 1X Release A system may support radio data services. The 1x EVDO (hereinafter the ‘EVDO’) system was developed for supporting high speed radio data service.
The above-described two radio systems may be different in their modulating and demodulating methods, although they may use the same frequency band and the same code division multiplexing. Accordingly, a dual mode mobile terminal that can simultaneously support the two radio systems has been developed in order to complementarily receive a service from both radio systems.
One characteristic of the 1x Release A system is the ability to provide simultaneous voice and data service. During voice communication, a user can receive data service by setting a new data call without cutting off voice communication. On the other hand, while receiving data service, a user can additionally perform voice communication whenever necessary. The voice communication may include an outgoing call and an incoming call.
On the other hand, since the EVDO system is devised only for the purpose of providing data service, simultaneous voice and data service has not been provided from the radio system. Accordingly, in a situation that a data call has been previously set in the EVDO system, an additional voice communication service cannot be provided in disadvantageous arrangements. However, a user having a dual mode mobile terminal may not know and may not care about the kind of radio system being used to provide the service. Accordingly, the user may want to receive both voice and data services regardless of the kind of system that is currently connected thereto. Therefore, a method is desired for overcoming differences between two radio systems of a dual mode terminal and providing the user with the same functions.